Author Topic: FP 40 gone wild (Read 13527 times)

Steve Helmick · « **Reply #50 on:** July 12, 2017, 11:27:09 PM »

Not long ago, I posted part of Leonard Neumann's (sp?) venturi chart in another thread. No, I don't recall what size engines the section of the chart was for. But in general, .272" bore with a .156" spraybar (AKA 4mm) is a good start, which can be easily toned down with a few layers of nylon mesh trimmed from 2nd hand pantyhose. Tim does this, himself.

The interesting thing is that a .272" bore with .156" spraybar through on center is a good start on .25 to .76 engines, because the bigger engines pump more air through the same throat area. Perfect, no. But it saves a lot of math. I've used .272"/.156" on .25LA, XLS .36, and .46LA engines. My PA .51...dunno. OS .46VF...dunno. PA has the offset spraybar like a lot of Super Tigres did, so the bore is much smaller, and I don't recall what it is, but I think the .46VF is .272", but it's a Randy Aero engine, and I haven't checked the venturi bore.

I'd kinda like to post the whole chart once and have it "pinned", but it's not up to me. I have the file, if anybody can pin it someplace. I've reworked it some to try and get the columns straight and the column headers lined up. Frustrating, the computer program used didn't like that, but it's better than it was. Numbers are the same, all I did was put a lot of time into fine-tuning the chart a little to make it easier to read...multiple pages of it. <sigh>

Frankly, I strongly dislike "clicker" type NV assemblies, most especially the OS ones. Yes, they work nice while they work nice. But they can be damaged, look ok, but don't work worth a spit. I'd rather have them look broken when they're broken! I'm hoping you'll play with the ones you have, if you like them. Randy's are the best!

Steve

Brett Buck · « **Reply #51 on:** July 13, 2017, 12:42:14 AM »

Quote from: Steve Helmick on July 12, 2017, 11:27:09 PM

I'd kinda like to post the whole chart once and have it "pinned", but it's not up to me. I have the file, if anybody can pin it someplace.

I really wish you wouldn't. It happens to be in the ballpark in this case (because its in the center of the range) but it is wildly wrong at the ends. The premise is faulty as well.

Brett

Tim Wescott · « **Reply #52 on:** July 13, 2017, 09:59:51 AM »

Quote from: Brett Buck on July 13, 2017, 12:42:14 AM

I really wish you wouldn't. It happens to be in the ballpark in this case (because its in the center of the range) but it is wildly wrong at the ends. The premise is faulty as well.

Brett

We need the Brett Buck chart. Or the Brett Buck/Randy Smith chart, if you two agree.

Chris Fretz · « **Reply #53 on:** July 13, 2017, 06:51:17 PM »

Ok we are looking at .008 up and down slop on the bushing. The crank is reading. 001-.002 runout.

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RandySmith · « **Reply #54 on:** July 13, 2017, 07:56:53 PM »

Crank is good , the bushing is worn, may work or maybe some of the vibration problem, I would be happier with .004 thou

Randy

Chris Fretz · « **Reply #55 on:** July 13, 2017, 07:59:58 PM »

Ok crank #2 was reading .003 runout. However my lathe and cheap China collet was giving me inconsistant readings I would get one time reading .006 runout and then another time I would get get .003. On the backplate I would get anywhere from .008 to .004 pretty much on both. So the inconsistent readings are rather disappointing. But it's an old lathe too.

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Chris Fretz · « **Reply #56 on:** July 13, 2017, 08:03:13 PM »

Randy I couldn't get the 1/4 in backplate adapter to fit any of my 1/4 28 shafts. Got a good fix for that?

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Dan McEntee · « **Reply #57 on:** July 13, 2017, 09:21:28 PM »

Way back when in the early 90's I think it was, there was a bit in Stunt News about the best set up for an OS FP.40. This was the era of the desk top published newsletter that Windy or Mike Keville or one of the other early editors put out. It consisted of the smaller of the two venturis that came with the control line version at that time, one head shim, and as little exhaust restriction as you could get and still use a muffler, and no more that 4" pitch or something like that. I pretty much followed that recipe and always had good luck, once I got the idea out of my head that I could make a Graupner 10-6 three blade prop work on it! I had a bone stock FP.40 in a SIG Mustang Stunter back then that I never had a bad run on. I found and used some Tornado 10-6 three blade props on that model and they worked well, mainly because they were actually a 4" pitch. I also remember reading then that others had good luck with them when mounted inverted in a stunt model. Some weird quirk of physics helps with things in that position. I have read where guys dislike the LA.40 for stunt and do all sorts of plugging a such to bypass ports and head shims and such. I used one of those on my Dusty profile model in bone stock configuration following the same recipe that was in Stunt News all those years ago and I think I have a .250" Russ Gifford venturi in it with a OS needle valve assembly when it is in stunt rim, and I was very impressed with the power it made when I have the stunt set up on it. Uses right at 4 ounces of fuel for the pattern and uses a MAster Airscrew 10-5 three blade for a prop.. For scale flying with throttle, that venturi comes off and a carburetor goes on with electronics pack with receiver, servo and battery. The prop is a very important part of the equation, and you may have to try several brands to find what works best on a particular airplane. It is just a matter of experimentation and test flying.
Type at you later,
Dan McEntee

Carl Cisneros · « **Reply #58 on:** July 13, 2017, 11:07:34 PM »

Chris
The tank set up on the PF is pretty much fool proof.
Solid run from start to tank finish.

Carl

RandySmith · « **Reply #59 on:** July 13, 2017, 11:08:28 PM »

Quote from: #Liner on July 13, 2017, 08:03:13 PM

Randy I couldn't get the 1/4 in backplate adapter to fit any of my 1/4 28 shafts. Got a good fix for that?

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yES TAKE some alum or brass tube and use it over the shaft to bush it to fit the backplate hole, or just turn a bushing on your lathe easy ..

Randy

RandySmith · « **Reply #60 on:** July 13, 2017, 11:09:27 PM »

Quote from: RandySmith on July 13, 2017, 11:08:28 PM

yES TAKE some alum or brass tube and use it over the shaft to bush it to fit the backplate hole, or just turn a bushing on your lathe easy ..

Randy

Or ream the adapter out till it fits

Chris Fretz · « **Reply #61 on:** July 14, 2017, 02:50:06 AM »

Quote from: RandySmith on July 13, 2017, 11:09:27 PM

Or ream the adapter out till it fits

Plenty of options, thanks Randy.

Chris Fretz · « **Reply #62 on:** July 14, 2017, 02:51:26 AM »

Quote from: Carl Cisneros on July 13, 2017, 11:07:34 PM

Chris
The tank set up on the PF is pretty much fool proof.
Solid run from start to tank finish.

Carl

Who makes that tank? I've never seen one like it.

Chris

Carl Cisneros · « **Reply #63 on:** July 14, 2017, 08:07:12 AM »

Chris
I can not remember who makes that tank.
Got it a long time back.

Carl

Chris Fretz · « **Reply #64 on:** July 14, 2017, 09:46:16 AM »

Quote from: Motorman on July 14, 2017, 09:14:51 AM

It's not as easy as you might think. I've made a good number of the SuperTiger style and I prefer to buy. It's a good pet to have if you need a custom length or diameter but allot of work.

MM

I was thinking the same thing. Some things just aren't worth making.

Dennis Moritz · « **Reply #65 on:** July 18, 2017, 07:30:36 PM »

We fly lots of FP40s and Tower40s in our club. We like them. Cheap power that can be made to work. Our formula differs some from Randy. In many ways we overlap. Runaway has many causes. Vibration, wrong fuel, bad choice of prop, restrictive muffler, attempting to run the engine in a bad rpm range, usually too slow. Which is why I cringe when this topic comes up. Hard to diagnose at a distance.

Here are a few starter points. Good running FP40s and Tower40s burn 4.5 to 5 ounces of fuel when running right. Sometimes even more. If you're not burning that much fuel, open up the muffler. Use a bigger venturi, if the plane you are flying is over 40 ounces. I also wonder why none of the folks who offer advice here, ask, what plane, what weight. Model weight, design drag, hugely effect these engines. I had a 27 ounce magician that flew very well with a stock Tower 40, two extra head gaskets, and a mid size .273 venturi. Broke in right places. That plane went in when the controls let go after a way over spec pull test. My immediate next model was a somewhat porky Prowler, 45 ounces. Engine set up greatly changed.

RknRusty · « **Reply #66 on:** July 18, 2017, 11:18:33 PM »

Don't you have a box of metal tubing bits?

Chris Fretz · « **Reply #67 on:** July 20, 2017, 08:39:40 PM »

Quote from: Dennis Moritz on July 18, 2017, 07:30:36 PM

We fly lots of FP40s and Tower40s in our club. We like them. Cheap power that can be made to work. Our formula differs some from Randy. In many ways we overlap. Runaway has many causes. Vibration, wrong fuel, bad choice of prop, restrictive muffler, attempting to run the engine in a bad rpm range, usually too slow. Which is why I cringe when this topic comes up. Hard to diagnose at a distance.

Here are a few starter points. Good running FP40s and Tower40s burn 4.5 to 5 ounces of fuel when running right. Sometimes even more. If you're not burning that much fuel, open up the muffler. Use a bigger venturi, if the plane you are flying is over 40 ounces. I also wonder why none of the folks who offer advice here, ask, what plane, what weight. Model weight, design drag, hugely effect these engines. I had a 27 ounce magician that flew very well with a stock Tower 40, two extra head gaskets, and a mid size .273 venturi. Broke in right places. That plane went in when the controls let go after a way over spec pull test. My immediate next model was a somewhat porky Prowler, 45 ounces. Engine set up greatly changed.

On 4.5oz I could definitely have gotten about 3-4 full patterns in. I'll get back to messing with the FP40 in a week or 2, too much going on right now.

Chris

Quote from: RknRusty on July 18, 2017, 11:18:33 PM

Don't you have a box of metal tubing bits?

You mean for the spinner backplate? I do have some laying around, I just haven't looked to see if I have all the right sizes.

Chris

Target · « **Reply #68 on:** July 20, 2017, 09:20:57 PM »

My fp40 flies plenty long on 4oz. But my plane is only 38oz.

Dennis Moritz · « **Reply #69 on:** July 21, 2017, 06:26:08 AM »

4.5 ounces plus of fuel running through an FP40 and clones helps cooling. This will assist stabilizing the run.

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Target · « **Reply #70 on:** July 21, 2017, 07:28:57 AM »

Dang, I'll have to put on a bigger tank now....

Matthew Brown · « **Reply #71 on:** November 13, 2017, 06:00:25 AM »

Sorry for bringing this back up, but I was planning on making some venturis for my FPs and LAs. I was wondering if there is any gain or negatives to mounting the NVA higher in the venturi. Mostly I just didn’t want to drill out the case to accept a PA NVA. I figured easiest way was to mount the venturi like the RC carb with screws and put the NVA higher up in the body of the venturi.

Thanks, Matt

Dennis Moritz · « **Reply #72 on:** November 13, 2017, 08:58:40 PM »

Arf Primary Force has a weak nose. Probably complicating your run. I put a 1/8" rectangular aluminum plate on the inside of fuse of the one I had. Engine mounting bolts used were long enough to bolt through to the plate, going through a hole drilled in each corner. Plate slightly larger than engine mount outline. Lock nuts were cinched tight every few flights. If they were not, bad vibes and run run runaway. Cinched very tight. Washers of course were used under the heads of the mounting screws. Not uncommon for me to break the black screws after a few flight sessions. That's how tight. With this particular bird, doing that, calmed it down. Free flowing tongue muffler always important. In Philly we often run larger than 260 venturis when plane weight is above 40 ounces. It's necessary to flow sufficient fuel through engine to keep it cool. Look to burn 4.5 plus ounces in a pattern. Some FPs tolerate less fuel flow, most don't. Tower 40 is an excellent copy of the FP40. Not exact. Improvement over the FP. True chrome liner instead of the softer nickel in the FP40. I've had Tower 40s retain stall a starter compression season after season. Cylinder head has deeper cooling fins. Looks as though the compression dish is shallower on the Tower. Head gaskets of the Tower are 10 thou, head gaskets of the FP are 15thou. You might try a .273 venturi with the stock needle valve. That, along with a free flowing muffler, will increase fuel flow through engine increasing the cooling.

Weight of plane, drag of plane, vibes of the construction. And so forth. All play a role in engine run. We even had an FP40 calm down when the old needle valve was replaced. Tolerances had apparently grown over the years, needle vibrating in screw seat.

In Philly we work with these engines season in and season out. Almost always we get them to run effectively enough in competition. They are not PAs, RoJett's or good running Super Tigres. But they can be had cheap and can be worked with. Way more powerful than the older baffle piston 35s.

Fuel suggestions are similar to what we use. Powermaster 22%, 50/50, 5 and 10%.

What tank. Don't run uniflo if you are having any runaway issues. Uniflo can aggravate any fuel foaming issues.

We almost always run 10.5x4.5 APC props.

My Galaxy is posted. Shows the aluminum plate. A Tower 40 has powered this plane for ten years. Chicken hopper tank. For 7 years I ran it on muffler pressure and uniflo. One day that stopped working, solid engine run started to be a wee erratic. Taking it off uniflo fixed that.

Chris Fretz · « **Reply #73 on:** November 15, 2017, 05:27:20 AM »

Quote from: MattBrown on November 13, 2017, 06:00:25 AM

Sorry for bringing this back up, but I was planning on making some venturis for my FPs and LAs. I was wondering if there is any gain or negatives to mounting the NVA higher in the venturi. Mostly I just didn’t want to drill out the case to accept a PA NVA. I figured easiest way was to mount the venturi like the RC carb with screws and put the NVA higher up in the body of the venturi.

Thanks, Matt

That is a interesting idea to avoid drilling. Depending on what you are putting it in, you may not have a problem on a profile set up but you may run into a tank height problem in a full body airplane with the needle valve being so much higher up. However I am no expert on set up's. If I was you I would start a new topic in engine set up and tips to get more experts to help you out.

Chris

Matt Brown · « **Reply #74 on:** August 31, 2018, 05:34:13 PM »

Popping this back to the top. I’ve read through every post.
I have an FP40 in a Nobler arf. It has a nylon venturi with a .256 bore. I have a PA NVA mounted in the original location. Using Sig Champion 10% fuel. It has an RSM tongue muffler. The plastic tank it came with plumbed for Uniflow. I have tried both Xoar 11-4 and TT 11-4.5.
It does exactly like someone described earlier in the thread, running away.
Timed a couple laps before I did any maneuvers it sounded great and was running a decent 5.25- 5.30 lap. After just a couple maneuvers it leaned out and stayed that way the rest of the flight, running steady but fast 4.40 laps.
I assume it has only the stock head shim as I’ve never added any. Per most of what I have read through this thread, I should be getting decent runs but definitely not so far. The only thing that occurs to me is maybe the RSM tongue muffler is too restrictive.

What do the FP40 fans say?
Worst case, I can do the head mod but I tend to agree with those that feel that isn’t the way to go.

Thanks, Matt

Dane Martin · « **Reply #75 on:** August 31, 2018, 06:06:46 PM »

Quote from: Matt Brown on August 31, 2018, 05:34:13 PM

Popping this back to the top. I’ve read through every post.
I have an FP40 in a Nobler arf. It has a nylon venturi with a .256 bore. I have a PA NVA mounted in the original location. Using Sig Champion 10% fuel. It has an RSM tongue muffler. The plastic tank it came with plumbed for Uniflow. I have tried both Xoar 11-4 and TT 11-4.5.
It does exactly like someone described earlier in the thread, running away.
Timed a couple laps before I did any maneuvers it sounded great and was running a decent 5.25- 5.30 lap. After just a couple maneuvers it leaned out and stayed that way the rest of the flight, running steady but fast 4.40 laps.
I assume it has only the stock head shim as I’ve never added any. Per most of what I have read through this thread, I should be getting decent runs but definitely not so far. The only thing that occurs to me is maybe the RSM tongue muffler is too restrictive.

What do the FP40 fans say?
Worst case, I can do the head mod but I tend to agree with those that feel that isn’t the way to go.

Thanks, Matt

My opinion....
If you're gonna leave the engine stock, but use a tongue muffler, you should start with a .200 venturi and a stock os nva. Now, if your nva is fatter, you'll just need to match a venturi to get the same choke area as that set up.
Set it screaming highest rpm you can get and back it off enough clicks to keep it from roasting in the air. Basically I ran mine like a 25 set up. High rpm low pitch. The setting remains the same from start to finish

Air Ministry . · « **Reply #76 on:** August 31, 2018, 08:27:36 PM »

Quote

Sorry for bringing this back up, but I was planning on making some venturis for my FPs and LAs. I was wondering if there is any gain or negatives to mounting the NVA higher in the venturi. Mostly I just didn’t want to drill out the case to accept a PA NVA. I figured easiest way was to mount the venturi like the RC carb with screws and put the NVA higher up in the body of the venturi.

Thanks, Matt

Like Wot Thisis Ere Eh .

Upright / Inverted , tankll need to be ' in line ' , so if close could hinder cooling airflow aft . Perhaps .

SIDEWINDER Fashion , . . .

This & a OS 40 Four Stoke I observed . . .

Both with TANK outer Edge / at / level / almost inside even , the Spray Bar Line . Longitudeinaly . Inside Laterally Rotationally

;

Good Rich ' Four Stoke ' ( What Else do you xpect of a four stroke OS 40 $:-\$ ) at ' level flight .

As the Full weight ? of fuels loading the feed , Higher you go the less ' head ' it has , so set for o.k. , not to lean , overhead ( 8's )
Lower you go the richer it gets . Which was basically a good set up for this ( 25 ) in a Nobler size sucker .

The Uniflow Vent was stright out the inboard side , whacked of at 45 degree or a bit flatter - into the airstream .

So it ' could ' be a Gun Set Up , for these nasty schneurle OS 40 things . of which I unfortunately have a few . Gotta New 44 GP Magnum now to , a clone .
NOW YOUVE DONE IT .
Might try this intake in that , as its ' cinch bar ' type & Im loath to cross drill the case .

RandySmith · « **Reply #77 on:** September 01, 2018, 05:16:03 PM »

Quote from: Matt Brown on August 31, 2018, 05:34:13 PM

Popping this back to the top. I’ve read through every post.
I have an FP40 in a Nobler arf. It has a nylon venturi with a .256 bore. I have a PA NVA mounted in the original location. Using Sig Champion 10% fuel. It has an RSM tongue muffler. The plastic tank it came with plumbed for Uniflow. I have tried both Xoar 11-4 and TT 11-4.5.
It does exactly like someone described earlier in the thread, running away.
Timed a couple laps before I did any maneuvers it sounded great and was running a decent 5.25- 5.30 lap. After just a couple maneuvers it leaned out and stayed that way the rest of the flight, running steady but fast 4.40 laps.
I assume it has only the stock head shim as I’ve never added any. Per most of what I have read through this thread, I should be getting decent runs but definitely not so far. The only thing that occurs to me is maybe the RSM tongue muffler is too restrictive.

What do the FP40 fans say?
Worst case, I can do the head mod but I tend to agree with those that feel that isn’t the way to go.

Thanks, Matt

Hi Matt

You should read my post about NOT using a .255 venturi for a ST or PA NVA, and NOT using a .281 for a OS 20 NVA, IF you use a PA assembly use the .281, a .255 is too small, and it is choking the motor down, cutting down the fuel/oil burn, and if using restrictive muffler, runaway.... if you use the STOCK OS 20 NVAs, then YES use the .255, it is about the same as a .281 with the St or PA OR the OLD OS 35 40 NVA

Randy

Dennis Toth · « **Reply #78 on:** September 03, 2018, 10:07:47 AM »

Chris,
The FP 40 likes to run pretty high rpm. I think you should try dropping the prop diameter first to 10 1/2"x4 maybe even go to 10" diameter. Most of the problem is heat. Use a good NVA that doesn't leak air (either an ST or one of Randy's PA NVA). Think low pitch/high rpm. Let it spin up to a rich 2 cycle and adjust your line length and pitch (could go to 3 3/4 or 3 1/2 pitch) to get the lap time you need. I like wood props (RMS or BY&O), they are light and can be heat pitch just like an APC prop does. Think about the way they run the FP 20, they launch at 11K. Stop trying to fight the engine and use the power to pull the ship.

Best, DennisT

rich gorrill · « **Reply #79 on:** September 04, 2018, 01:11:37 PM »

I realize this is an old thread, but just want to interject I have had the same problem with an FP20. I put it on a newly built ringmaster from Eric Rule this spring and the same thing happened as Chris describes with his LA 40. I had no vibration problem but it "ran away" as soon as the plane went airborne. My solution was to install an LA 25 and that solved the problem. My point is this problem also happens with the FP 20. I used a stock OS needle valve and the small OS venture and an 8-4 prop.

Brett Buck · « **Reply #80 on:** September 04, 2018, 01:19:55 PM »

Quote from: rich gorrill on September 04, 2018, 01:11:37 PM

I realize this is an old thread, but just want to interject I have had the same problem with an FP20. I put it on a newly built ringmaster from Eric Rule this spring and the same thing happened as Chris describes with his LA 40. I had no vibration problem but it "ran away" as soon as the plane went airborne. My solution was to install an LA 25 and that solved the problem. My point is this problem also happens with the FP 20. I used a stock OS needle valve and the small OS venture and an 8-4 prop.

Again, that is not an engine defect. The problem is that the engine is *way too much power* for a Ringmaster when running correctly, meaning, it goes way too fast in flight.

The needle is not a throttle and is only capable of tiny speed change range, if you want different overall power, use a smaller venturi or a smaller engine. Or use the stock RC carb and use that to control the speed.

Brett

phil c · « **Reply #81 on:** September 10, 2018, 06:09:42 AM »

Chris-
"This hobby will make you broke fast. "

You ain't seen nothing like going broke until you try quarter scale 3D RC flying, or getting a few of the Yatsenko PA models. Multiple thousands just to get in the air. And you lose it all in a bad crash.

Target · « **Reply #82 on:** September 10, 2018, 02:54:49 PM »

That's nothing.
How about 3K for a carbon fiber sailplane airframe, then 6x 80-100 bucks for digital servos? (X2 or 3 to compete)
1500 dollars for an f3b winch (x2), special 12v winch batteries, 400m spools of mono (25 bucks each, could last 1 flight or 5 flights).
All that and no fuel or motor.

Author Topic: FP 40 gone wild (Read 13527 times)

Matthew Brown